[Mesa-dev] gallium: blitters and scissors

Christoph Bumiller e0425955 at student.tuwien.ac.at
Fri Oct 15 06:45:22 PDT 2010


 On 13.10.2010 05:50, Corbin Simpson wrote:
>
> Yes, that particular part of the spec is fairly Poulsboriffic. Does
> any open hardware have a scissor enable/disable bit?
>
Heh, does nv hardware count as "open" in that regard ?
nv50+ do have scissor enable bits, for each of the 16 scissor rects,
but the blob doesn't use them; we do.

> Sending from a mobile, pardon the brevity. ~ C.
>
> On Oct 12, 2010 8:47 PM, "Dave Airlie" <airlied at gmail.com
> <mailto:airlied at gmail.com>> wrote:
> > On Wed, Oct 13, 2010 at 1:07 PM, Dave Airlie <airlied at gmail.com
> <mailto:airlied at gmail.com>> wrote:
> >> On Wed, Oct 13, 2010 at 12:07 PM, Dave Airlie <airlied at gmail.com
> <mailto:airlied at gmail.com>> wrote:
> >>> I've noticed that none of the blitters use scissor state, and wondered
> >>> if there was a reason for this.
> >>>
> >>> It looks like drivers are expected to setup scissor state in the
> >>> framebuffer setup and in the set scissor state, but with r600g due to
> >>> the underlying state tracking it can end up doing the wrong thing.
> >>>
> >>> The 3 patches add CSO cache + u_blit + u_blitter scissor usage.
> >>>
> >>> Just wondering if I'm violating some rules of the gallium
> interface or not.
> >>
> >> I realised this was a quite deep hole I started digging in mesa/st,
> >> any advice on whether cleaning it up is a good idea?
> >>
> >
> > Okay so it helps to read the docs, since it the scissor state enable
> > relies on a bit in the rasterizer state.
> >
> > So it looks like we should always set scissor regs in the framebuffer
> > state and only modify them if we notice
> > the rasterizer bit is enabled.
> >
> > Dave.
> > _______________________________________________
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>
>
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